Touch-sensing panel and force detection

ABSTRACT

Disclosed is a touch position sensor. Force detection circuitry can be included with the position sensor, for example, to determine an amount of force applied to a touch panel of the sensor.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/129,863, filed Sep. 13, 2018, which is a divisional of U.S. patentapplication Ser. No. 14/981,510, filed Dec. 28, 2015, now U.S. Pat. No.10,146,351, which is a continuation of U.S. patent application Ser. No.12/959,166, filed Dec. 2, 2010, now U.S. Pat. No. 9,223,445, all ofwhich are incorporated herein by reference.

BACKGROUND

A position sensor can detect the presence and location of a touch by afinger or by an object, such as a stylus, within an area of an externalinterface of the position sensor. In a touch sensitive displayapplication, the position sensor enables, in some circumstances, directinteraction with information displayed on the screen rather thanindirectly via a mouse or touchpad. Position sensors can be attached toor provided as part of devices with a display. Examples of displaysinclude, but are not limited to, computers, personal digital assistants(PDAs), satellite navigation devices, mobile telephones, portable media,players, portable game consoles, public information kiosks, and point ofsale systems. Position sensors have also been used as control panels onvarious appliances.

There are a number of different types of position sensors. Examplesinclude, but are not limited to, resistive touch screens, surfaceacoustic wave touch screens, capacitive touch screens, and the like. Acapacitive touch screen, for example, may include an insulator coatedwith a transparent conductor in a particular pattern. When an object,such as a finger or a stylus, touches the surface of the screen them isa change in capacitance. This change in capacitance is sent to acontroller for processing to determine the position where the touchoccurred.

In a mutual capacitance configuration, for example, an array ofconductive drive electrodes or lines and conductive sense electrodes orlines can be used to form a touch screen having capacitive nodes. A nodemay be formed at each intersection of a drive electrode and a senseelectrode. The electrodes cross at the intersections but are separatedby an insulator so as to not make electrical contact. In this way, thesense electrodes are capacitively coupled with the drive electrodes atthe intersection nodes. A pulsed or alternating voltage applied on adrive electrode will therefore induce a charge on the sense electrodesthat intersect with the drive electrode. The amount of induced charge issusceptible to external influence, such as from the proximity of anearby finger. When an object approaches the surface of the screen, thecapacitance change at every individual node on the grid can be measuredto determine the location or position of the object.

SUMMARY

Disclosed are various examples of a touch sensor that includes exemplaryforce detection circuitry. The force detection circuitry can be used todetermine an amount of force applied to the sensor.

BRIEF DESCRIPTION OF THE FIGURES

The figures depict one or more implementations in accordance with thepresent teachings, by way of example only, not by way of limitation. Inthe figures, like reference numerals refer to the same or similarelements.

FIG. 1 illustrates schematically a cross-sectional view of a touchsensitive panel;

FIG. 2 illustrates schematically a plan view of conductors of the touchsensitive position-sensing panel of FIG. 1 together with a controller ofa touch sensitive panel;

FIG. 3 is a circuit diagram of a first example of a force sensor useabletogether with the controller of a touch sensor;

FIG. 4 is a circuit diagram of a second example of a force sensoruseable together with the controller of a touch sensor; and

FIG. 5 is a circuit diagram of a third example of a force sensor useabletogether with a controller of a touch sensor.

DETAILED DESCRIPTION

In the following detailed description, numerous specific details are setforth by way of examples in order to explain the relevant teachings. Inorder to avoid unnecessarily obscuring aspects of the present teachings,those methods, procedures, components, and/or circuitry that arewell-known to one of ordinary skill in the art have been described at arelatively high level.

Reference now is made in detail to the examples illustrated in theaccompanying figures and discussed below.

A display may be overlaid with a touch position-sensing panel, toimplement a touch sensitive display device. The display may includevarious forms. Examples include, but are not limited to liquid crystaldisplays such as an active matrix liquid crystal display, anelectroluminescent display, an electrophoretic display, a plasmadisplay, cathode-ray display, an OLED display, or the like. It will beappreciated that light emitted from the display should be able to passthrough the position-sensing panel with minimal absorption orobstruction.

FIG. 1 illustrates an exemplary touch position-sensing panel 1 whichoverlies a display 2. Although the force sensing may be used in touchsensors implementing other types of touch sensing, for discussionpurposes, the drawing shows an example of a structure that may be usedto implement a mutual capacitance type touch sensitive panel.

In the illustrated example, the panel 1 includes a substrate 3 having asurface on each side. The panel 1 includes a first number of electrodes4(X) and a second number of electrodes 5(Y) provided on the oppositesurfaces of the substrate 3. The substrate 3 is also provided adjacentto the display 2 such that one electrode 4(X) is between the display 2and the substrate 3. An air gap is formed between the display 2 and thefirst electrode 4(X). A transparent adhesive layer 6 is between thesecond electrode 5(Y) and a transparent covering sheet 7.

In other examples, the touch position-sensing panel 1 may have a secondsubstrate (not shown). With a second substrate, a touch position-sensingpanel may have a transparent panel, a first adhesive layer on the panel,a first electrode layer forming first electrodes, a first substrate, asecond adhesive layer, a second electrode layer forming secondelectrodes, and the second substrate. In such an example, the firstconductive electrode layer is attached to the first substrate and thesecond conductive electrode layer is attached to the second substrate.

Returning to the illustrated example of FIG. 1, substrate 3, which formsa core of the exemplary touch sensitive position-sensing panel 1, can beformed from a transparent, non-conductive material such as glass or aplastic. Examples of suitable plastic substrate materials include, butare not limited to Polyethylene terephthalate (PET), PolyethyleneNaphthalate (PEN), or polycarbonate (PC).

In the mutual capacitance example, electrodes 4(X) are drive electrodesprovided on one surface of the substrate 3, and electrodes 5(Y) aresense electrodes provided on the opposing surface of the substrate 3.Capacitive sensing channels are formed at the capacitive coupling nodeswhich exist in the localized regions surrounding where the first andsecond electrodes 4(X) and 5(Y) cross over each other and are separatedby the non-conductive substrate 3.

Transparent covering sheet 7 is provided over the substrate 3 andelectrodes 5(Y) and may be joined thereto using various methods andmaterials. One exemplary implementation is a pressure-sensitiveadhesive. In one example, the covering sheet 7 may be glass,polycarbonate, or PMMA.

Indium-tin-oxide (ITO) is an example of a clear conductive material thatcan be used so form either one or both sets of electrodes 4(X) and 5(Y)in the example of FIG. 1. Alternatively, any other clear conductivematerial may be used, such as other inorganic and organic conductivematerials, such as Antimony-tin-oxide (ATO), tin oxide, PEDOT or otherconductive polymers, carbon nanotube or metal nanowire impregnatedmaterials, and the like, Further, opaque metal conductors may be usedsuch as a conductive mesh, which may be of copper, silver or otherconductive materials.

With reference to FIG. 2, drive electrodes 4(X) and sense electrodes5(Y) are formed by solid areas of ITO. Sensing area 10 of the positionsensing panel 1, denoted by the dotted line in FIG. 2, encompasses anumber of the intersections 11 formed by the drive electrodes 4(X) andsense electrodes (5)Y. In the example, the gaps between adjacent Xelectrode bars are made narrow. This may enhance the ability of theelectrodes 4(X) to shield against noise arising from the underlyingdisplay 2 shows in FIG. 1. In some examples, 90% or more of the sensingarea 10 is covered by ITO. In an example like that shown in FIG. 2, thegap between adjacent drive electrodes 4(X) may be 200 microns or less.

In one example, each drive electrode 4(X) forms channels with a numberof the sense electrodes 5(Y) on an adjacent plane. As mentionedpreviously, there are intersections 11 where the drive electrodes 4(X)cross over the sense electrodes 5(Y).

A drive electrode connecting line 12 is in communication with arespective drive electrode 4(X). A sense electrode connecting line 13 isin communication with a respective sense electrode 5(Y). The patterns ofthe connecting lines are shown by way of an example only. The driveelectrode connecting lines 12 and the sense electrode connecting lines13 are connected to a control unit 20.

In some examples, the change in capacitance at the node formed at eachintersection 11 of drive electrode 4(X) and sense electrode 5(Y) when anobject touches the surface of the panel 1 can be sensed by the controlunit 20. The control unit 20 applies pulsed or alternating voltages tothe drive electrodes 4(X) through the drive electrode connecting lines12. The control unit 20 measures the amount of charge induced on thesense electrodes 5(Y) through the sense electrode connecting lines 13.The control unit 20 determines that a touch has occurred and thelocation of the touch based upon the changes in capacitance sensed atone or more of the nodes 11.

In some examples, the amount of charge induced on a sense electrode 5(Y)can be measured by a current integrator circuit 22 incorporated in thecontrol unit 20. The current integrator circuit 22 can measure theaccumulated charge on a capacitor at fixed time intervals. The exemplarycontroller 20 includes a number “n” of current integrators 22 a, 22 b, .. . 22 n and a processor 23. Some of these integrators are used in theprocessing of signals from the sensing channels to detect touch on thetouch position-sensing panel 1.

Some touch sensor applications may take advantage of a measurement ofthe amount of force applied to the touch position-sensing panel 1. Forsuch an application of the touch sensor, a force sensor can beassociated with the touch position-sensing panel 1 and controller 20.The force sensor, in some examples, measures the amount of force appliedto the transparent covering sheet 7 of the touch position-sensing panel1. The force sensor may be used to quantify or distinguish betweendifferent types of touch events. For example, the force sensor canmeasure the amount of force applied and cause the execution of a firstfunction if the force is below or equal to a threshold. The force sensorcan also measure the amount of force applied and cause the execution ofa second function if the force exceeds the threshold.

With reference back to FIG. 1, a resistive force sensitive element 30can be used to measure the amount of force applied to the panel. In oneexample, the resistive force sensitive element 30 can be arrangedbetween the touch position-sensing panel 1 and a supporting structure(not shown). In another example, the touch position-sensing panel 1 isincorporated in a portable device with the resistive force sensitiveelement 30 arranged between the touch position-sensing panel 1 and ahousing of the device.

The resistive force sensitive element 30, for example, may be formed ofa Quantum Tunneling Composite material (QTC). The DC resistance of theQTC material varies in relation to applied force. In one example, theforce sensitive element 30 can be formed by printing an ink containingthe QTC material.

With reference back to FIG. 2, in some examples, the resistive forcesensitive element 30 can modulate the flow of current into a currentintegrator circuit 22 of the control unit 20. The control unit 20 caninclude one or more current integrator circuits 22 that are not used intouch sensing operations. One exemplary controller 20 is the mXT224 soldby Atmel Corporation, of San Jose Calif. Using such a controller 20facilitates force sensing by using existing circuitry of the controlunit 20. Thus, force sensing can be achieved, in some examples, withoutany additional dedicated electronic conditioning circuitry such as biasnetworks, amplifiers, analogue to digital converters, and the like.

With reference to FIG. 3, a first exemplary circuit 32 that includes aresistive force sensitive element 30 is shown and described. The circuit32 is in communication with an input of a current integrator 22 of thecontrol unit 20. The control unit 20 is connected to a ground rail 19and a fixed voltage supply rail 27 that has a voltage V_(dd). Aresistive force sensitive element 30 having a value R_(Q) is connectedbetween the fixed voltage supply rail 27 and the current integratorinput 21 of the control unit 20. The current integrator input 21 acts asa virtual earth having a voltage V_(n). Having the resistive forcesensitive element 30 and the control unit 20 both connected to the samevoltage supply rail 27 allows the circuitry within the control unit 20,which measures the integrated current value, to be referenced to thevoltage supply rail. This configuration may also allow the measurementto be made ratiometric and substantially decoupled from any changes inthe supply rail voltage V_(dd). Although the supply rail voltage V_(dd)can be a fixed voltage, there may be unintended fluctuations in thesupply rail voltage V_(dd).

A limit resistor 24 having a value R_(L) is connected in series with theresistive force sensitive element 30, between the fixed voltage supplyrail 27, and the current integrator input 21. The limit resistor may,for example, have a resistance value in the range 100Ω to soon. Thelimit resistor 24R_(L) limits the maximum current flow through theresistive force sensitive element 30 to the current integrator input 21if the resistance of the resistive force sensitive element 30 drops to alow value. This configuration can prevent the current from exceeding amaximum value that can be accepted and measured by the currentintegrator 22. The resistance of some QTC materials can drop to arelatively low value when subjected to a large applied force.

A bias resistor 25 having a value R_(B) is connected between the fixedvoltage supply rail 27 and the limit resistor 24 in parallel with theresistive force sensitive element 30. In some instances, the resistanceof some QTC materials can rise to a high value when not subjected to anapplied force. The bias resistor 25 provides a DC current path if theresistance of the resistive force sensitive element 30 rises to a veryhigh value. The bias resistor 25 may, for example, have a resistancevalue of 1 MΩ or more.

In this configuration, the value of the current flow I_(n) into theintegrator input 21 will be approximately:I_(n)=(V_(dd)−V_(n))/(((R_(Q)*R_(B))/(R_(Q)+R_(B)))+R_(L)).

In this example, each of the values in this equation other than I_(n)and R_(Q) are fixed. However, the current I_(n) is a function of changein the force sensitive resistance R_(Q). Accordingly, the resistancevalue R_(Q) of the resistive force sensitive element can be determinedfrom the value of the accumulated charge obtained by integration ofI_(n) over a fixed time as measured at the current integrator input 22.The value of the applied force can in turn be determined from theresistance value R_(Q) of the resistive force sensitive element. Theforce can be calculated based on the characteristic of the QTC materialusing the calculated resistance. In some applications the force appliedmay not need to be accurately calculated; instead a simple threshold onthe output of the integrator performing the force measurement may besufficient to provide information to the host system.

The determined force can be used to cause certain events to occur inresponse thereto. For example, if the portable device is a mobile phoneand the force applied to an area of the touch sensitive-position panel 1exceeds a threshold value, then the mobile phone may perform a firstaction. For example, the menu of the mobile phone can return to a homescreen. However, if the force does not exceed the threshold, then themenu may not change or a different action can occur. In addition, morethan one threshold can be used to trigger various events. Some eventscan be triggered when a threshold is met and exceeded. Other events canbe triggered when the force is below or equal to the threshold. Someevents can be triggered when the threshold is exceeded. Other events canoccur when the force is below the threshold. Still further actions canbe performed based directly on the applied force. Examples include, butare not limited to, a zoom-in action may be applied where the level ofzoom being proportional to the applied force.

With reference to FIG. 4, another circuit 33 that includes a QTCresistive force sensitive element 30 is shown and described. Theresistive force sensitive element 30 is in communication with a controlunit 20. The control unit 20 is connected to a ground rail 19 and afixed voltage supply rail 27 that has a voltage V_(dd).

In this example, the resistive force sensitive element 30 has aresistance R_(Q) and is connected between a voltage driver output 26 ofthe control unit 20 and at an input 21 of a current integrator 22 of thecontrol unit 20. The voltage driver output 26 supplies an alternatingvoltage varying between a high voltage and a low voltage while thecurrent integrator input 21 acts as a virtual earth at a voltage midwaybetween the high and low voltages. In particular, the voltage driveroutput 26 supplies an alternating voltage varying between a high voltagesubstantially equal to the supply rail voltage V_(dd) and a low voltageof substantially zero volts at ground, while the current integratorinput 21 acts as a virtual earth at a voltage V_(n) which isapproximately half of V_(dd). Although the alternating voltage is apositive voltage relative to the ground voltage, the alternating voltageis an alternating bi-polar voltage relative to the virtual earth at thecurrent integrator input. The voltage driver can also drive one or moredrive electrodes 4(X).

In this example, the current integrator input 21 voltage is nominallymidway between the high and low voltages of the alternating voltage.However, other values of the current integrator input voltage betweenthe high and low voltages could be used. The value of the current:integrator input voltage will depend on how the alternating voltagevaries with time.

In some examples, the voltage driver output 26 of the control unit 20used to supply the alternating voltage to the resistive force sensitiveelement 30 may also be used to drive a drive electrode 4(X) of the touchposition sensing panel 1. In such a configuration, the force sensor 30may be shielded by being placed behind a conductive ground plane. Othertypes of shielding can also be used. Shielding can prevent capacitivecoupling that can cause the force sensing element to become touchsensitive as well as force sensitive. In various applications this maybe undesirable as the force sensor should respond to the force appliednot to the proximity of the object applying the force.

Supplying the force sensing element 30 with an alternating voltagehaving values that are above and below the voltage of the currentintegrator input 21 can allow the circuits within the control unit 20used to measure the integrated current value to carry out differentialmeasurement of the current flow through the resistive force sensitiveelement 30. Such differential measurement may facilitate noisecancellation for some types of noise.

A limit resistor 24 having a resistance R_(L) is connected between thevoltage driver output 26 and the current integrator input 21. The limitresistor 24 is connected in series with the resistive force sensitiveelement 30.

A bias resistor 25 having a resistance R_(B) is connected between thevoltage driver output 26 and the limit resistor 24. The bias resistor 25is connected in parallel with the resistive force sensitive element 30.

The resistance value R_(Q) of the resistive force sensitive element canbe determined from current values measured by differential currentmeasurement at the input 21 of the current integrator 20. The value ofthe applied force can in turn be determined from the resistance valueR_(Q) of the resistive force sensitive element. The force can bedetermined based on the characteristics of the QTC material using thecalculated resistance.

With reference to FIG. 5, another example of a circuit 34, is shown anddescribed. The circuit 34 includes three QTC resistive force sensitiveelements 30 a, 30 b, and 30 c in communication with the control unit 20.Also, the control unit 20 is connected to a ground rail 22 and a fixedvoltage supply rail 27 that has a voltage V_(dd).

In this example, each of the resistive force sensitive elements 30 a, 30b, 30 c is connected to a respective voltage driver output 26 a, 26 b,26 c of the control unit 20. All of the resistive force sensitiveelements 30 a, 30 b, 30 c, also are connected to an input 21 of acurrent integrator 22 of the control unit 20. Each voltage driver output26 a, 26 b, 26 c periodically supplies an alternating voltage varyingbetween a high voltage and a low voltage. The current integrator input21 acts as a virtual earth at a voltage midway between the high and lowvoltages. In particular, each voltage driver output 26 a, 26 b, 26 csupplies an alternating voltage varying between a high voltage equal tothe supply rail voltage V_(dd) and a low voltage of zero volts atground. In addition, the current integrator input 21 acts as a virtualearth at a voltage V_(n) which is half of V_(dd). In some examples, eachvoltage driver output 26 a, 26 b, 26 c of the control unit 20 used tosupply the alternating voltage to a resistive force sensitive element 30a, 30 b, 30 c may also be used to drive a drive electrode of the muchposition sensing panel.

The timing of the periodic operation of the three voltage driver outputs26 a, 26 b, 26 c may be synchronized so that one of the three voltagedriver outputs 26 a, 26 b, 26 c is emitting an alternating voltage atany time. Accordingly, a single current integrator input 21 can measurethe current flow through each of the resistive force sensitive elements30 a, 30 b, 30 c in turn.

A respective limit resistor 24 a, 24 b, 24 c, is connected between eachvoltage driver output 26 a, 26 b, 26 c and the current integrator input21 in series with a respective resistive force sensitive element 30 a,30 b, 30 c.

A respective bias resistor 25 a, 25 b, 25 c is connected between eachvoltage driver output 26 a, 26 b, 26 c and a respective limit resistor24 a, 24 b, 24 c in parallel with a respective resistive force sensitiveelement 30 a, 30 b, 30 c.

The resistance value of each resistive force sensitive element 30 a, 30b, 30 c can be determined from the respective current values determinedby differential current measurement at the current integrator input 21during the respective driver intervals. For each force sensing element30 a, 30 b, 30 c, the value of the applied force can in turn bedetermined from the determined resistance value of the respectiveresistive force sensitive element. The force can be determined based onthe characteristics of the QTC material using the calculated resistance.

In this example, the resistance values of three resistive forcesensitive elements 30 a, 30 b, 30 c, are measured using a single currentintegrator input 21. Other numbers of current integrators 22 can also beused.

As shown, the resistance values of multiple resistive force sensitiveelements 30 a, 30 b, 30 c are measured using multiple voltage driveroutputs 26 a, 26 b, 26 c and a single current integrator input 21. Inother examples, a single voltage driver output 26 and multiple currentintegrator inputs 21 could be used. In yet other examples, multiplevoltage driver outputs 26 and multiple current integrator inputs 21could be used. For example, N voltage driver outputs 26 and M currentintegrator inputs 21 could be arranged to measure N×M resistive forcesensitive elements 30.

In the previous examples, limit resistors 26 are shown. However, limitresistors 26 may not be included if the characteristics of the resistiveforce sensitive element 30 are such that the resistance of the resistiveforce sensitive element is sufficiently high that the maximum currentflow through the resistive force sensitive element is acceptable to thecurrent integrator 22. Further, limit resistors 26 may not be used inthe illustrated circuits if the current integrators 22 include anintegral limit resistor.

In the illustrated examples, bias resistors 25 are used. However, biasresistors 25 may not be included if the characteristics of the resistiveforce sensitive element 30 are such that the resistance of the resistiveforce sensitive element 30 is sufficiently low that a DC current paththrough the resistive force sensitive element exists.

In the illustrated examples, force sensitive resistance elements 30provide a force sensor. However, other types of resistive elements canalso be used to provide additional sensing functionality. For example,light dependent resistance elements, infra red dependent resistanceelements, or temperature dependent resistance elements can also be used.Each of these types of elements provides one or more additional sensingfeatures in addition the position sensing provided by the driveelectrodes 4(X) and sense electrodes 5(Y).

In the illustrated example, the drive electrodes 4(X) and the senseelectrodes 5(Y) may be formed as two separate layers, However, otherarrangements are possible. The mutual capacitance touch position sensorcan alternatively be formed as a single layer device having co-planardrive electrodes and sense electrodes both formed on the same surface ofa single substrate.

In the illustrated examples, the drive electrodes 4(X) and senseelectrodes 5(X) may be rectangular strips. However, other arrangementsare possible. The shape of the drive and sense electrodes and theinterconnection between the channels of any given electrode may bemodified according to the type of touch with which the position sensingpanel is intended to be used. For example, the stripes may havesaw-tooth or diamond shaped edges with attendant, inter-stripe gaps tofacilitate field interpolation to aid in smoothing positional response.

The number of drive electrodes and sense electrodes shown is by way ofillustration only, and the number shown is not limiting.

While the above discussion used mutual capacitance drive approaches forthe discussions of examples of the sensors that may incorporate forcesensors, self-capacitance drive adapted to include force sensing byapplication of the technologies discussed in the examples above.

Various modifications may be made to the examples described in theforegoing, and any related teachings may be applied in numerousapplications, only some of which have been described herein. It isintended by the following claims to claim any and all applications,modifications and variations that fall within the true scope of thepresent teachings.

What is claimed is:
 1. A mobile electronic device comprising: a housing;a capacitive touch sensing panel comprising: a substrate having a firstsurface; a plurality of drive electrodes or sense electrodes of a touchsensor disposed on the first surface; a plurality of drive electrodes orsense electrodes of the touch sensor disposed on a second surface,wherein if a plurality of drive electrodes is disposed on the firstsurface, a plurality of sense electrodes is disposed on the secondsurface, wherein if a plurality of sense electrodes is disposed on thefirst surface, a plurality of drive electrodes is disposed on the secondsurface, and wherein the plurality of drive electrodes is comprised of aclear conductive material; a display; a cover sheet, wherein the firstsurface of the substrate is configured to face towards the cover sheet;and an optically clear adhesive layer (OCA) disposed between the firstsurface of the substrate and the cover sheet; one or more processorscomprising a voltage driver and an integrator circuit, the voltagedriver configured to provide an alternating voltage; a first variableresistance electrode coupled to an output of the voltage driver and aninput of the integrator circuit, wherein the integrator circuit isconfigured to measure a parameter of the first variable resistanceelectrode, wherein the first variable resistance electrode is configuredto be driven by the alternating voltage provided by the voltage driver,and wherein the first variable resistance electrode is disposed betweenthe capacitive touch sensing panel and the housing; the one or moreprocessors configured to determine, based on the measured parameter, anamount of force applied to a sensing area of the capacitive touchsensing panel; and the one or more processors further configured todetermine whether the amount of force exceeds a first threshold value,and if the amount of force exceeds the first threshold value, cause themobile electronic device to trigger a first event.
 2. The mobileelectronic device of claim 1, wherein: the substrate further comprisesthe second surface; the first surface is opposite the second surface;and the second surface of the substrate is configured to face towardsthe display.
 3. The mobile electronic device of claim 1, wherein theparameter of the first variable resistance electrode is measured over aperiod of time.
 4. The mobile electronic device of claim 1, wherein: theclear conductive material is selected from the group consisting ofindium-tin-oxide (ITO), antimony-tin-oxide (ATO), tin oxide, and aconductive polymer; the substrate is comprised of at least one of glass,polyethylene terephthalate (PET), polyethylene naphthalate (PN), orpolycarbonate (PC); and the cover sheet is comprised of at least one ofglass, polycarbonate, or polymethylmethacrylate (PMMA).
 5. The mobileelectronic device of claim 4, wherein the display is an organiclight-emitting diode (OLED) display.
 6. The mobile electronic device ofclaim 5, wherein the one or more processors is further configured todetermine whether the determined amount of force exceeds a secondthreshold value, and if the amount of force exceeds the second thresholdvalue, cause the mobile electronic device to trigger a second event thatis different from the first event.
 7. The mobile electronic device ofclaim 6, wherein the one or more processors is further configured todetermine whether the determined amount of force exceeds a thirdthreshold value, and if the amount of force exceeds the third thresholdvalue, cause the mobile electronic device to trigger a third event thatis different from the first event and different from the second event.8. The mobile electronic device of claim 1, wherein the first event isselected from the group consisting of returning to a home screen andzooming in on a particular region of the display.
 9. The mobileelectronic device of claim 1, wherein the measured parameter is currentflowing through the first variable resistance electrode.
 10. A mobileelectronic device comprising: a housing; a capacitive touch sensingpanel comprising: a cover sheet; optically clear adhesive (OCA); aplurality of sense electrodes of a touch sensor, wherein the pluralityof sense electrodes is comprised of conductive metal mesh; and adisplay; one or more processors comprising a voltage driver and anintegrator circuit, the voltage driver configured to provide analternating voltage; a first variable resistance electrode coupled to anoutput of the voltage driver and an input of the integrator circuit,wherein the integrator circuit is configured to measure a parameter ofthe first variable resistance electrode, and wherein the first variableresistance electrode is configured to be driven by the alternatingvoltage provided by the voltage driver; and the one or more processorsconfigured to determine, based on the measured parameter, an amount offorce applied to a sensing area of the capacitive touch sensing panel,determine whether that amount of force exceeds a first threshold value,and if the amount of force exceeds the first threshold value, cause themobile electronic device to trigger a first event.
 11. The mobileelectronic device of claim 10, wherein the conductive metal mesh iscomprised of copper or silver.
 12. The mobile electronic device of claim11, wherein the one or more processors is further configured todetermine whether the determined amount of force exceeds a secondthreshold value, and if the amount of force exceeds the second thresholdvalue, cause the mobile electronic device to trigger a second eventdifferent from the first event.
 13. The mobile electronic device ofclaim 10, wherein the display is an organic light-emitting diode (OLED)display.
 14. The mobile electronic device of claim 13, wherein the firstevent is selected from the group consisting of returning to a homescreen and zooming in on a particular region of the display.
 15. Themobile electronic device of claim 14, wherein the measured parameter iscurrent flowing through the first variable resistance electrode.
 16. Amobile electronic device comprising: a housing; a capacitive touchsensing panel comprising: a cover sheet; optically clear adhesive (OCA);a plurality of drive electrodes of a touch sensor and a plurality ofsense electrodes of a touch sensor, wherein the plurality of driveelectrodes and the plurality of sense electrodes are comprised ofconductive metal mesh; and a display; one or more processors comprisinga voltage driver and an integrator circuit, the voltage driverconfigured to provide an alternating voltage; a first variableresistance electrode coupled to an output of the voltage driver and aninput of the integrator circuit, wherein the integrator circuit isconfigured to measure a parameter of the first variable resistanceelectrode, wherein the first variable resistance electrode is configuredto be driven by the alternating voltage provided by the voltage driver,and wherein the first variable resistance electrode is disposed betweenthe capacitive touch sensing panel and the housing; and the one or moreprocessors configured to determine, based on the measured parameter, anamount of force applied to a sensing area of the capacitive touchsensing panel, determine whether that amount of force exceeds a firstthreshold value, and if the amount of force exceeds the first thresholdvalue, cause the mobile electronic device to trigger a first event. 17.The mobile electronic device of claim 16, wherein the conductive metalmesh is comprised of copper or silver.
 18. The mobile electronic deviceof claim 17, wherein the one or more processors is further configured todetermine whether that amount of force exceeds a second threshold value,and if the amount of force exceeds the second threshold value, cause themobile electronic device to trigger a second event that is differentfrom the first event.
 19. The mobile electronic device of claim 18,wherein the measured parameter is current flowing through the firstvariable resistance electrode.
 20. The mobile electronic device of claim16, wherein the display is an organic light-emitting diode (OLED)display.
 21. The mobile electronic device of claim 20, wherein the firstevent is selected from the group consisting of returning to a homescreen and zooming in on a particular region of the display.